Contact device

Abstract

A combined pivot joint and electric contact device between two welding current conductors forming part of the welding circuit of a resistance welder. The device is provided with a pair of contact plates extending at right angles to the joint axis and connected each to one of the welding current conductors. The plates are rotatable and axially displaceable with respect to each other. A yieldable thrust member urges the plates into engagement with each other. A channel provided in at least one of the plates has an outlet in the contact face of the plate and an inlet away from said face. Separation of the plates is effected by connecting the channel to a source of compressed gas to discharge a current of gas through the port.

We claim: 
     
       1. In a resistance welder, a combined pivot joint and electric contact device between two welding current conductors forming part of the welding circuit of the resistance welder, comprising: a joint pin,   a pair of flat contact plates extending at right angles to said joint pin and connected each to one of said conductors, said contact plates being supported for relative rotation about said joint pin and being axially displaceable with respect to each other between a contact position in which the contact plates engage each other and an idle position in which the contact plates are out of engagement with each other,   means for yieldably urging at least one of said contact plates towards the other contact plate, and   means for moving said contact plates out of engagement with each other including   a channel provided in at least one of the contact plates, said channel having an outlet port in the plate surface facing the other contact plate and an inlet, and,   means including a valve and a supply conduit for connecting said inlet to a source of compressed gas.   
     
     
       2. A device as claimed in claim 1 in which the contact plate which is connected to the source of compressed gas includes at least three channels having outlet ports which are evenly distributed around the pin axis. 
     
     
       3. A device as claimed in claim 2 in which each of said channels is connected to the supply conduit through a restricted passage. 
     
     
       4. A device for providing a pivot joint between a first and a second pair of welding current conductors forming part of a welding circuit of a resistance welder and for connecting the conductors of the second pair in series with the conductors of the first pair, the conductors of the first pair being connected to opposite terminals of a source of welding current so as to carry current in opposite directions, said device comprising: a joint pin;   two pairs of contact plates supported for relative rotation about said joint pin and forming an axial row of contact plates therein, the contact plates of a first one of said pairs of contact plates being connected each to one conductor of said first pair of conductors, and the contact plates of the second one of said pair of contact plates being connected each to one conductor of said second pair of conductors;   electrically insulating means for maintaining the contact plates of said first pair of contact plates axially stationary with respect to each other, the contact plates of said second pair of contact plates being axially displaceable each with respect to a corresponding one of the contact plates of said first pair of contact plates;   means for yieldably urging each of the contact plates of said second pair of contact plates into engagement with a corresponding one of the contact plates of said first pair of contact plates; and   means for moving each of the contact plates of said second pair of contact plates out of engagement with the corresponding contact plate of said first pair of contact plates including   a channel provided in at least one of the two contact plates arranged to engage each other, said channel having an outlet port in the plate surface facing the other of said two plates and an inlet, and   means including a valve and a supply conduit for connecting said inlet to a source of compressed gas.   
     
     
       5. A device as claimed in claim 4 in which the contact plates of said first pair of contact plates constitute the outer members of the axial row of contact plates. 
     
     
       6. A device as claimed in claim 5 in which the means for yieldably urging the contact plates of the second pair of contact plates into engagement with the corresponding contact plates of the first pair of contact plates is arranged axially between and is common to the contact plates of said second pair. 
     
     
       7. A device as claimed in claim 6 in which the means for yieldably urging the contact plates of the second pair of contact plates into engagement with the corresponding contact plates of the first pair of contact plates includes an expansible receptacle arranged to be connected to a source of compressed gas. 
     
     
       8. A device as claimed in claim 6 in which the means for yieldably urging the contact plates of the second pair of contact plates into engagement with the corresponding contact plates of the first pair of contact plates includes a pair of opposed, annular grooves in the adjacent faces of the contact plates of the second pair of contact plates, a conduit in one of said contact plates for connecting the space enclosed by said grooves to a source of compressed gas, and a pair of flexible sealing rings arranged to cover the gaps between said grooves.